1. Technical Field
The present disclosure relates in general to wireless communication devices and in particular to interference reduction in wireless communication devices.
2. Description of the Related Art
The ability to provide simultaneous voice and data communication service is a requirement for many network operators providing multiple types of transmission services. For example, Simultaneous Voice and Long Term Evolution (SVLTE) data transmission comprising Code Division Multiple Access (CDMA) 1X voice and LTE data transmission is a requirement for many CDMA/LTE operators. For intra-band SVLTE or simultaneous voice and data (SVDO), odd order reverse inter-modulation distortion (IMD) products generated by the power amplifier (PA) can cause desensitization to one or more receivers. The level of desensitization may be too high to be managed effectively using maximum output power reduction. A same issue is encountered during LTE uplink (UL) carrier aggregation.
Current approaches focus on mitigating IMD without addressing reverse IMD. In particular, the current approaches all relate to adjusting PA linearity to optimize current drain while still meeting transmitter specifications. These approaches do not attempt to mitigate reverse IMD, nor do they address dual transmit configurations which are required for SVLTE, SVDO, and UL carrier aggregation.
The conventional approach for dealing with SVLTE desensitization is to add extremely large ceramic filters. These ceramic filters increase insertion loss, degrade current drain and receiver sensitivity even when SVLTE is not being used. These filters do not help with intraband SVLTE, SVDO or intra-band carrier aggregation, since the two transmitters are operating in the same band. The use of isolators is another conventional approach for addressing SVDO desensitization. However, isolators increase insertion loss even when SVLTE/SVDO is not active and provide only a small and inadequate level of improvement.